Lipases are widely used in the reactions such as esterification of various carboxylic acids such as fatty acids with alcohols such as mono-alcohol and polyalcohol, and trans-esterification between plural carboxylates. Among these, when a lipase powder itself is used in esterification involving dehydrogenation, its activity does not fully express. Further, it is difficult to uniformly disperse the lipase powder into a reaction system, and also to recover it. Therefore, it is common to immobilize a lipase to some carriers, such as anion-exchange resin (Patent Literature 1), phenol adsorption resin (Patent Literature 2), a hydrophobic carrier (Patent Literature 3), cation-exchange resin (Patent Literature 4) and chelate resin (Patent Literature 5) and the like to use it in the reactions such as esterification reaction.
As mentioned above, a lipase has been conventionally immobilized and used in the esterification reaction. However, the immobilized lipase loses an original lipase activity through the immobilization. In addition, when a porous carrier was used, the raw materials and products have gotten stuck in fine pores and, as a result, the ratio of esterification decreases.
In light of the situations mentioned above, various technologies have been developed wherein a lipase powder is used. For example, a trans-esterification method is proposed wherein in the presence or absence of an inactive organic solvent(s), a lipase powder is dispersed into a raw material(s) containing ester in the trans-esterification in such a manner that 90% or more of the particles of the dispersed lipase powder can keep particle size of 1 to 100 μm in the reaction (Patent Literature 6). It is also proposed that enzyme powder is used, which is obtained by drying an enzyme solution(s) containing phospholipid and lipid-soluble vitamins (Patent Literature 7).
[Patent Literature 1] Japanese Patent Publication No. Sho 60-98984
[Patent Literature 2] Japanese Patent Publication No. Sho 61-202688
[Patent Literature 3] Japanese Patent Publication No. Hei 2-138986
[Patent Literature 4] Japanese Patent Publication No. Hei 3-61485
[Patent Literature 5] Japanese Patent Publication No. Hei 1-262795
[Patent Literature 6] Japanese Patent No. 2668187
[Patent Literature 7] Japanese Patent Publication No. 2000-106873